/* count.c -- 使用标准 I/O */

#include <stdio.h>
#include <stdlib.h>     // 提供 exti()的原型

int main(int argc, char * argv [])
{
    int ch;             // 读取文件时，存储每个字符的地方
    FILE * fp;      // “文件指针”
    unsigned long count = 0;

    if(argc != 2)
    {
        printf("Usage: %s filename\n", argv[0]);
        exit(EXIT_FAILURE);
    }
    if ((fp = fopen(argv[1], "r")) == NULL)
    {
        printf("Can't open %s\n", argv[1]);
        exit(EXIT_FAILURE);
    }
    while ((ch = getc(fp)) != EOF)
    {
        putc(ch, stdout);   // 与 putchar(ch); 相同
        count++;
    }
    fclose(fp);
    printf("File %s has %lu characters\n", argv[1], count);

    return 0;
}